In the
ESXi context,
the term target identifies a single storage unit that a host can access. The
terms device and LUN describe a logical volume that represents storage space on
a target.

The terms device and LUN mean a
SCSI volume presented to the host from a storage target.

Different storage vendors
present their storage systems to
ESXi hosts in
different ways. Some vendors present a single target with multiple LUNs on it.
Other vendors, especially iSCSI vendors, present multiple targets with one LUN
each.

Target and LUN
Representations

In
Target and LUN
Representations,
three LUNs are available in each configuration. On the left, the host sees one
target, but that target has three LUNs that can be used. Each LUN represents an
individual storage volume. On the right, the host sees three different targets,
each having one LUN.